In recent years, a variety of input apparatuses have been proposed in which piezoelectric elements are provided in a touch panel. When a user's finger, a stylus pen, or the like presses a target in a predetermined area of the touch panel, the input apparatuses detect input of the press and drive the piezoelectric elements, thus vibrating the touch panel so as to provide the user with an appropriate operational feeling. In a known touch panel apparatus, for example as illustrated in FIG. 8, at the back of each of the long sides of an oblong touch panel 51, a piezoelectric element 52 capable of expansion and contraction is disposed in the long side direction. The touch panel 51 is provided four-point support at the four corners by a fixing frame 54, with fixing cushions 53 therebetween, so as to be capable of flexure vibration (for example, see Patent Literature 1).
With the touch panel apparatus illustrated in FIG. 8, when the piezoelectric elements 52 on the long sides are driven to expand and contract in the long side direction at the same phase, the fixing cushions 53 elastically deform, and the touch panel 51 undergoes flexure vibration with the short sides as pivots as illustrated by the schematic perspective view in FIG. 9(a). Note that such flexure vibration is also referred to as bending vibration. As illustrated in FIG. 9(b), when the touch panel 51 is pressed by a finger 55, for example, the long sides of the touch panel 51 bend more than the short sides, i.e. the touch panel 51 flexes.
In such a touch panel apparatus as illustrated in FIG. 8, the flexure vibration direction of the touch panel 51 due to the piezoelectric elements 52 matches the bending direction of the touch panel 51 due to the press by the finger 55. Accordingly, when the touch panel 51 is being pressed, as illustrated in FIG. 9(b), the touch panel 51 may be caused by the piezoelectric elements 52 to undergo flexure vibration more efficiently. Furthermore, since the touch panel 51 bends due to elastic deformation of the fixing cushions 53, the same amount of expansion and contraction yields a larger vibration amplitude than when the piezoelectric elements 52 are provided on the short sides of the touch panel 51, thus offering the advantages of a reduction in size of the piezoelectric elements 52 and reduced costs.